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Spice model syntax
Spice model syntax
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Old 4th January 2004, 09:11 PM   #1
Netlist is offline Netlist  Belgium
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Default Spice model syntax

Most libraries come with a bunch of bundled models, all starting with
.subckt and ending with .end.
In between, the model is defined and all odd numbers seem to correspond to the pinout given in the .subckt line.

On the first line we see .SUBCKT (Device) 1 2 3 33 31 4 5 6 7 36 37
Lines starting with a star, meaning a comment. This I know.
What do these numbers stand for? They correspond with pin numbers of the IC, but why not
1 2 3 4 5 6 7 8 and so on?
All the other lines are not very straightforward too, so could someone please explain?
A small extraction of the whole model:
D2 15 6 DD
C3 6 7 2.20E-11
G3 15 7 15 6 4.06E+00
R7 7 15 1E3
D3 7 16 DD
V1 18 16 5.70E+00
D4 17 7 DD
V2 17 19 5.70E+00
Also the lines with . MODEL at the end are not the most obvious to read.
Again a small example:
.MODEL QI1 NPN (BF=2.29E+03 IS=8E-16)
.MODEL QI2 NPN (BF=1.63E+03 IS=9.54E-16)

Itís difficult to give the full model, all are copyrighted.
It would be helpful if someone could give the basic rules of the syntax.


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Old 4th January 2004, 10:08 PM   #2
crown300 is offline crown300
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Location: pittsboro, NC
I'm not an expert but here goes..........
At a guess, the numbering scheme you refer to started out as a simple model (for example an early op-amp) that got improved to where the new model kept most of the old models numbers and the improvements were added in, hence the 123 33 31 456.
(if I write a spice model I find it helps me to use 1-9 for inputs, 20 - 29 for outs, maybe 30-39 for another section.....)

The "D" stands for diode, "R" for resistor, "C" for capacitor.

the MODEL DD D( -- is a standard Diode model but the CJO parameter is 0.1pF instead of whatever the standard value is.
(CJO= zero-bias junction capacitance)

Have you been to:
or here,look on left for Transistors and Diodes:
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Old 5th January 2004, 07:04 AM   #3
Netlist is offline Netlist  Belgium
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Thanks crown,
I'll have a closer look there.

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